To produce pressurized air with an air pump, the air pump is provided with a compression chamber unit wherein the air is being compressed.
An air pump, e.g. for pumping air into a deflated tire, must quickly pump a certain amount of air at a certain pressure.
Previously, the applicant formed the compression chamber unit by die casting of the whole compression chamber unit in one process. Hence, the compression chamber unit was one unit with at least one outlet nozzle, a number of connecting flanges and a number of connecting bosses.
The above method is in some ways disadvantageous, as the die casting process lacks accuracy as regards the forming of a number of compression chamber units of the same volume, the right cylindrical form and with a smooth surface. Hence, additional processes must be carried out.
E.g. for reducing friction the surface must be smooth, thus it requires polishing, and it is necessary to roll the compression chamber units to provide the right cylindrical form and specific volume. Hence, friction reduction causes a reduction in the compression chamber unit heat development.
Furthermore, the die casting process is disadvantageous because of suction in the material, hence making the distribution of the material uneven, thereby reducing the number of usable compression chamber units.
Another disadvantage is that the die casting process requires a slip angle of the die cast compression chamber unit in order to remove the compression chamber unit from the cast.
Others have tried to solve this problem by using a cylindrical body part with a cap. However, this is disadvantageous as it requires a sealing ring for ensuring an air-tight compression chamber unit.
Due to the temperature difference which is caused by the compression of air or by movement of the air pump between different environments, the thickness of the sealing ring differs, and the volume of the compression chamber unit changes, hence making it difficult to calculate the specific compression chamber unit volume.
Furthermore, wear and tear of the sealing ring significantly increases the risk of the non-air-tight compression chamber unit becoming defect.